1. Field of the Invention
This invention relates to an electric bulb socket mounted on a wall of a lamp house and more particularly to such a bulb socket to which an electric bulb having an electrode on the bottom of a cylindrical base thereof is attached.
2. Description of the Prior Art
FIG. 8 illustrates a prior art electric bulb B and a prior art socket for the bulb B. The electric bulb B comprises a bulb section m and a base n. The base n has side electrode o formed on its side and a bottom electrode p formed on its bottom. The electric bulb socket comprises a cylindrical housing a having on the outer peripheral wall thereof a mounting portion b at which the socket is mounted on a panel P of a lamp house. A closure c closes one of two ends of the socket housing. The base n of the electric bulb B is inserted into the socket housing a through its other open end, and thus, the open end side of the socket housing a serves as a socket section. Two generally J-shaped slots (not shown) each beginning at the open end of the socket housing a are formed in the inner peripheral wall of the socket section. Two mounting protrusions q of the electric bulb B are inserted into and engaged with the respective J-shaped slots such that the electric bulb B is attached to the bulb socket. When the electric bulb B has been attached to the bulb socket, the side electrode o provided on the side of the base n is connected to a side terminal (not shown) which is connected to an electric supply line W. Furthermore, the bottom electrode p is brought into contact with a bottom terminal e provided on an insulating bottom plate f and connected to the electric supply line W. The bottom plate f is urged by a coil spring d whose one end is held on the closure c. The bottom terminal e is pressed against the bottom electrode p against an urging force exerted by the coil spring d when the electric bulb B has been attached to the bulb socket, whereby the bottom terminal e is brought into contact with the bottom electrode p.
In the electric bulb socket of the above-described type, the socket housing a needs to have a length corresponding to the sum of the length of the base n which is inserted into the socket housing a and the length of the coil spring d disposed in series with the base n in the socket housing a. In consideration of an amount of expansion and contraction, exerted force of the coil spring and the like, the length of the coil spring cannot freely be reduced. Consequently, the electric bulb has its limit when the length of the socket housing a is reduced for the purpose of rendering the electric bulb small. Accordingly, the bulb socket is compelled to project rearwardly to a considerable degree when mounted on the panel P. Thus, the reduction in the length of the bulb socket has been desired.